Peppermint shows significant evidence of efficacy for pain control. Peppermint molecules are effective as both anti-nausea and analgesic agents. There is excellent pharmacologic evidence that peppermint blocks Substance-P, the main pain neurotransmitter in the nervous system. Aside from pain, Substance-P is also involved in nausea, anxiety, depression and inflammation. Peppermint has been used to treat post-herpetic neuralgia, trigeminal neuralgia, chronic low back pain, neck pain, migraine and chronic daily headache, inflammatory pain, nerve pain and irritable bowel pain. One of peppermint’s main components is menthol, a soothing substance when placed on the skin. It is used in various rubs and ointments to activate cold temperature receptors on the skin and reduce musculoskeletal pain. Additionally, peppermint evokes a feeling of well being and has a positive effect on mood.

There is good evidence that lemon scent improves mood. Lemon has the highest concentration of a substance common to all citrus, limonene. There is no evidence that lemon reduces acute pain, but it appears to have the ability to bolster the immune system and reduce chronic inflammation.

Various scents stimulate pleasure circuits, and are helpful in counteracting pain. This active stimulation of pleasure circuits is a very powerful strategy and can ultimately become a direct replacement for abnormal pain. Pain and pleasure circuits are located in the same are of the brain. They each have their respective neurotransmitters. When the neurotransmitters of a stimulated pleasure circuit are released, pain neurotransmitters are suppressed.